Dystopian novel set in a futuristic London which is largely underwater. Our main characters, Kara and Joe, live in the shanties; Joe's a 'beef' - someone who dives for treasures. They're orphans, poor and longing for a way out - they can't think beyond their next meal - until Joe, surfacing from a dive, is almost killed by a Mariner on a jetski. The Mariner swerves to avoid Joe and dies; his last words "I'm sorry" accompany a strange drawing that he gives to Joe. And so Joe and Kara are propelled into an endless, endless, endless, often confusing, game of cat and mouse between the Mariners, who hate the land-dwelling 'mudfoots', the mysterious Redeye and current London leader Remmick. Kara is captured and escapes, captured and escapes, captured and escapes...It turns out that no-one with any power can be trusted - they're all as bad as each other. Plenty of action, but not much of a character arc - think junior James Bond, somewhat soggy.